LP Ripping

As in previous years, the 2010 RMAF featured a full program of seminars. I moderated two of them, the first of which on Saturday morning featured Channel D's Rob Robinson demonstrating how to rip LPs to your PC. Rob flew by the seat of his pants, doing everything in full view of the packed houseincluding booting-up his Mac mini, hooking up a Music Hall turntable to a preamplifier/ADC and connecting the preamp to the computer with a FireWire linkto make the point that there was nothing intimidating about the process. (His and my thanks to AudioEngine for providing powered speakers to allow the audience to hear what was happening.) The only departure from orthodoxy was that as Robinson was using Channel D's Pure Vinyl program (reviewed by Michael Fremer last August) to capture the data, he was using the program's digital-domain RIAA correction so used a flat-response preamp rather than a true phono preamplifier.

What I found especially fascinating was that with the first LP he rippeda 45rpm reissue of some classic Elvis Presley songs that he just purchasedthere was spectral content on some finger pops going all the way up to 100kHz! Robinson was therefore ripping the LP at 192kHz in order to preserve the waveform cut into the LP's grooves with as much accuracy as possible. Those who argue that even 44.1kHz is overkill for ripping LPs, please take note.

The latest research into hearing and the brain indicates that even if, on the measurement level, we cannot "hear" 100 kHz finger pops, their presence absolutely affects our appreciation of the sound. Hence, high-resolution files played through speakers whose tweeters and super tweeters extend way beyond 20K DO make a difference.

Submitted by John Atkinson (not verified) on October 22, 2010 - 10:51am

As I wrote, Rob Robinson's philosophical basis is to preserve the waveform, which will include its ultrasonic content, as accurately as possible. The question as to whether that ultrasonic content is audible is a different one. As Jason Serinus said, there is some published research that ultrasonic energy does affect perception, though it is a stretch to say that is it audible as such.

Thanks, Jason and John, for your thoughts.Capturing audio above 20 kHz is done for the sake of preservation of the waveform, and avoiding the "brick wall" of the antialiasing filter. The filter wipes out everything above (ca. 20 kHz), while also introducing other artifacts (phase shift). I won't get into issues of audibility above 20 kHz, but I won't argue against it, either; and there may be other mechanisms by which humans can perceive ultrasonic content.That aside, why capriciously throw that content away, especially when digital storage is so inexpensive nowadays? If one argues that including content above 20 kHz and 24 bit resolution are overkill for vinyl transfers, then the raison d'étre for high definition digital in general must be called into question, as well. (Consider that 24 bit audio is about far more than just raw dynamic range.)I will say the following slightly tongue in cheek, but: high definition digital has finally caught up to what 50 year old analog is capable of...! ;-)

Mr. Robinson, thank you so much for a superb demonstration. I was very close to buying your product and will now definitely do so (the coupon helped too). Sorry I didn't notice the needle guard was still on until after it had been resting on the record for a while.